Pension And Other Postretirement Benefits (Summary Of Plan Asset Allocations) (Details)	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan Asset Allocation, Equity	62.00%	61.00%
Target Plan Asset Allocation, Equity	60.00%	60.00%
Plan Asset Allocation, Fixed Income	36.00%	35.00%
Target Plan Asset Allocation, Fixed Income	35.00%	35.00%
Plan Asset Allocation, Cash	2.00%	4.00%
Target Plan Asset Allocation, Cash	5.00%	5.00%
Target Plan Asset Allocation, Total	100.00%	100.00%
Plan Asset Allocation, Total	100.00%	100.00%
Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan Asset Allocation, Equity	36.00%	53.00%
Target Plan Asset Allocation, Equity	38.00%	60.00%
Plan Asset Allocation, Fixed Income	56.00%	40.00%
Target Plan Asset Allocation, Fixed Income	54.00%	30.00%
Plan Asset Allocation, Other	8.00%	7.00%
Target Plan Asset Allocation, Other	8.00%	10.00%
Target Plan Asset Allocation, Total	100.00%	100.00%
Plan Asset Allocation, Total	100.00%	100.00%

Defined Benefit Plan Cash

No definition available.

Name:	pom_DefinedBenefitPlanCash
Namespace Prefix:	pom_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Defined Benefit Plan Fixed Income

+ References

No definition available.

+ Details

Name:	pom_DefinedBenefitPlanFixedIncome
Namespace Prefix:	pom_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Defined Benefit Plan Target Allocation Percentage Of Assets Cash

+ References

No definition available.

+ Details

Name:	pom_DefinedBenefitPlanTargetAllocationPercentageOfAssetsCash
Namespace Prefix:	pom_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Defined Benefit Plan Target Allocation Percentage Of Assets Fixed Income

+ References

No definition available.

+ Details

Name:	pom_DefinedBenefitPlanTargetAllocationPercentageOfAssetsFixedIncome
Namespace Prefix:	pom_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Defined Benefit Plan Target Allocation Percentage Total

+ References

No definition available.

+ Details

Name:	pom_DefinedBenefitPlanTargetAllocationPercentageTotal
Namespace Prefix:	pom_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The percentage of the fair value of equity securities to the fair value of total plan assets held as of the measurement date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph d(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 5

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e2446-114920

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (d)(1)

-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanEquitySecurities
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The percentage of the fair value of investments other than debt securities, equity securities, and real estate to the fair value of total plan assets held as of the measurement date.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanOtherPlanAssets
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Target allocation percentage of investments in equity securities to total plan assets presented on a weighted-average basis as of the measurement date of the latest statement of financial position.

+ References

No definition available.

+ Details

Name:	us-gaap_DefinedBenefitPlanTargetAllocationPercentageOfAssetsEquitySecurities
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Target allocation percentage in other than debt securities, equity securities, and real estate to total plan assets presented on a weighted-average basis as of the measurement date of the latest statement of financial position.

+ References

No definition available.

+ Details

Name:	us-gaap_DefinedBenefitPlanTargetAllocationPercentageOfAssetsOther
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The aggregate percentage of the fair value of investments (categorized by debt securities, equity securities, real estate and other plan assets) to the fair value of total plan assets held as of the measurement date.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant